1. Technical Field
The present invention relates to a control device of a gear processing machine having a workpiece axis that holds a workpiece, and a tool axis that has a tool for processing the workpiece.
2. Description of Related Arts
A gear processing machine to process a gear has a workpiece axis that holds a workpiece, and a tool axis that has a tool for processing the workpiece. These workpiece axis and tool axis must be driven in synchronization with each other.
FIG. 8 is a functional block diagram of a control device of a gear processing machine according to related art. In FIG. 8, a slave axis motor 130 drives a workpiece axis 300, and a master axis motor 230 drives a tool axis 400. As illustrated in FIG. 8, the slave axis motor 130 is controlled by a slave axis controller 120, and the master axis motor 230 is controlled by a master axis controller 220. These slave axis controller 120 and master axis controller 220 are connected to an upper controller 100 by buses 110 and 210, respectively. The upper controller 100 controls all the axes.
In addition, a speed detection sensor 140 provided in the slave axis motor 130 detects the rotation speed of the slave axis motor 130 and feeds this back to the slave axis controller 120. Also, a slave axis position detection sensor 150 detects the position of a slave axis (in this case, a workpiece axis 300) and feeds this back to the slave axis controller 120.
Similarly, the speed detection sensor 240 provided in the master axis motor 230 detects the rotation speed of the master axis motor 230 and feeds this back to the master axis controller 220. Also, a master axis position detection sensor 250 detects the position of a master axis (in this case, a tool axis 400) and feeds this back to the master axis controller 220.
In the event a helical gear or the like is processed by the gear processing machine illustrated in FIG. 8, it is necessary to apply twisting operations. In such cases, a synchronization command for allowing the workpiece axis 300 and the tool axis 400 to synchronize with each other, and a superimposition command for applying twisting operations, are combined in the upper controller 100, and supplied to the slave axis controller 120.
In FIG. 8, the position feedback data of the tool axis 400 that is detected by the master axis position detection sensor 250 is supplied to the upper controller 100, via the master axis controller 220 and a bus 210. Then, the upper controller 100 establishes synchronization by supplying this data to the slave axis controller 120 via the bus 110. Likewise, in Japanese Unexamined Patent Publication No. 4-238504, position feedback of a tool axis is supplied to an upper controller, and a workpiece axis is operated so as to synchronize with the position feedback.
FIG. 9 is another functional block diagram of a control device of a gear processing machine according to related art. In FIG. 9, a branch circuit 190 is provided to connect the master axis position detection sensor 250 and the slave axis controller 120. In FIG. 9, the position feedback data of a tool axis 400 that is detected by the master axis position detection sensor 250 is supplied to the branch circuit 190. Then, the branch circuit 190 branches and supplies the data to the controller 220 and slave axis controller 120, and, by this means, establishes synchronization.
However, with the gear processing machine illustrated in FIG. 8, in order to transfer the position feedback data of the master axis (tool axis) to the slave axis controller 120, it is necessary to pass the upper controller 100. Consequently, transmission delay is produced with the master axis (tool axis) position feedback data, and this makes synchronization of high accuracy difficult.
In addition, since the gear processing machine illustrated in FIG. 9 requires a branch circuit 190, the cost of the gear processing machine increases accordingly. Furthermore, the relationship between the master axis (tool axis 400) and the slave axis (workpiece axis 300) is electrically fixed, on a one by one basis, and it is therefore difficult to change the slave axis to another axis (not illustrated). Moreover, in FIG. 9, it is not possible to synchronize a plurality of slave axes with one master axis (tool axis 400).
The present invention has been made in view of the above, and it is therefore an object of the present invention to provide a control device of a gear processing machine, that reduces transmission delay and that allows one or a plurality of slave axes to synchronize with one master axis, without using a branch circuit.